"Morse is seedier in the books, definitely. I feel we should be bringing more of those elements into Endeavour. I really like that slightly unwholesome quality"David Brown, Radio Times

The Morse franchise continues to grow in 2013 as we look both forward and into the past. There are three new cases for Kevin Whately and Laurence Fox in Lewis (Mondays, ITV1), while spring sees a first full run of Endeavour.

This latest spin-off, charting Morse's early police career, arrives following a successful pilot in 2012 that netted an impressive 8.2m viewers. Not that star Shaun Evans feels complacent: "You can't go into this expecting a ready-made audience. I don't believe there is. If there are existing fans of the original series, then that's brilliant. I hope we can do something that they enjoy, but my hope is to get a new audience as well.

"We have to do our absolute best to offer more than what's gone before. Otherwise, what's the point?"

Evans has been finding inspiration in Colin Dexter's original Morse novels, where the DCI has an earthy interest in striptease and pornography, all-but ignored by the series starring John Thaw. "The books were my first point of contact with Morse. I prefer it that way because it's all in my head rather than it being how somebody else has done it. Those novels are great. I just loved them.

"And Morse is seedier in the books, definitely. I feel we should be bringing more of those elements into Endeavour. I really like that slightly unwholesome quality."

And, presumably, part of the appeal of playing a 1960s detective is that you also get to deduce properly, rather than rely on the trappings of modern-day crime dramas such as DNA tests and mobile phones? "Yes, that's what's interesting about it. Endeavour has to use his grey matter to find motive and reason for people's actions. And this is at a time when people were still shocked by the idea of murder."

But the deductions and period setting would count for naught if it weren't for our continuing fascination with the mystery of Morse himself. What, for instance, of his love life? After all, the character does have a reputation for falling for either the murder victim or the killer. Can we expect any happiness for young Endeavour?